Compasses of various kinds are known in the state of the art and are used for orienteering, i.e. the practice of using a compass, generally in combination with a topographic map, to determine a bearing or the route of travel. Commonly, classical or conventional compasses comprise a base member and a vial assembly pivotally coupled to the base member. The vial assembly comprises a vial and an azimuth ring as well as a magnetized indicator member pivotally journaled in the vial. Generally, the magnetized indicator member is a needle pointing to magnetic north. Moreover, an orienting marker is located in the vial. Commonly, the orienting marker is in form of an orienting arrow.
For taking a bearing for a destination visually, the compass is held level with a direction-to-travel arrow pointing towards the desired destination. For instance, the latter one can be a land mark like a mountain, a hill or a building. However, accurate sighting of a land mark and simultaneously taking a bearing is demanding and can lead to errors. To overcome such problems, the compass can be equipped with a hinged cover comprising a mirror and a sighting window or alternatively with a back sight. Such compasses are commonly called mirrored compasses. This allows sighting the land mark through the sighting window and simultaneously allows reading the needle alignment and azimuth ring in the reflection of the mirror.
Although usage of a mirrored compass greatly facilitates the sighting of a land mark and, hence, the handling of the compass, the sighting is still prone to inaccuracies caused by parallax, i.e. the apparent displacement of the landmark when viewed from different line of sights. Accordingly, when the line of sight through the sighting window is not essentially straight-lined, the bearing taken may still be inaccurate. This can lead to unintended detours or even to dangerous situations when one gets lost in the wilderness.
Thus, the objective of the present invention is to provide a compass which facilitates the sighting of a land mark through the sighting window.